Traditional security alarm system consists of security alarm control, access control, audible and voice warning device, etc. in order to achieve better security. However, no matter how integrated and intelligent the traditional burglary alarm systems are, they can be easily destroyed to lose its efficacy by a thief who is acquainted with the burglary alarm system. Since all appliances of the burglary alarm system demand on the power output of the burglary control panel, wires are linked from the control panel to each appliance respectively. Furthermore, the burglary control panel is installed at a predetermined location in house, such as in closet, storeroom, basement, attic, or near the entrance or exit. Although the burglary alarm system will be activated when burglars break in, experienced burglars can reach the control panel within a very short time and damage the control panel by immediately cutting all the wires connected therefrom. Once the control panel and wiring are vandalized by the intruder, the whole burglary alarm system is de-energized and loses its function and efficacy due to power lost.
To some more skillful burglars, there is a more simple way to achieve a power lost condition, which de-energizes the whole burglary alarm system, by burning the fuses in the control panel. Since the motion detectors and glass break detectors of the burglary alarm system are connected to the power source and located at those obvious places (such as the edges of doors and windows), burglars can simply short the power wires to burn out the fuses of control panel. Furthermore, the burglars can break or drill a hole on the window in order to reach the motion or glass break detectors and short the power wires immediately for burning the fuses. Thus, the whole burglary alarm system is de-energized and loses its function and efficacy.
U.S. Pat. No. 5,654,691 successfully solves the above problems by suggesting an auxiliary backup device of burglary alarm system which can monitor the voltage of the auxiliary power output from an burglary control panel. When the control panel and wiring are damaged, the auxiliary backup device will detect the interruption of the auxiliary power voltage and energize the output of an alarm device consisting audible and/or visual alarm to defer and prevent further damage from the intruder by an easy and economic way.
However, if a skillful burglary cut off its power supply or to electrically connect two power wires of the system warning device to cause electrical shock, the siren or sounder of the system warning device may still be de-activated, and thus the entire burglary alarm system as well as the auxiliary backup device can not provide warning alarm anymore. Moreover, the electrical relay circuit equipped in the auxiliary backup device is not as reliable as electronic components.